The present invention relates to oven door seals or the like and more particularly to a clipless door seal for ovens or the like.
The prior art teaches several different types of door seals. U.S. Pat. Nos. 1,998,791 (Schanz) and 3,140,517 (Richter) teach the use of an elongated element running the entire length of the seal for securing the seal to a surface. U.S. Pat. No. 2,823,660 (Holzboog) teaches the use of a cotter pin attached behind the door wall for securing the seal to a surface. U.S. Pat. No. 3,732,646 (Horvay) uses a foamed plastic body member as the securing and sealing element. U.S. Pat. Nos. 3,765,400 (Meier), 3,810,483 (Vonderhaar), 4,077,389 (Vogel), 4,223,660 (Lang), 4,248,017 (Micallef), and 4,417,420 (Marsh) teach the use of some form of metallic clip attached to the ends of the seal for securing the seal to a door surface. U.S. Pat. No. 4,512,331 (Levi) teaches the use of an integral cylindrical retaining portion interfit in a door gap for securing the seal to a surface.
The prior art devices have several disadvantages. The Schanz or Richter retaining elements require a continuous groove in the door or oven surface for securing the seal onto the surface. If a cotter pin is used, it must be secured to the seal from behind the surface which the seal is being secured. Alternatively, foamed plastic materials are not capable of withstanding the increased temperatures incurred in conventional oven operations. Metal securing clips require the metallic clip to be secured to the rubber seal encountering labor expense, or, in the case of Vonderhaar, both significant labor expense and significant expense for the bonding material. Vonderhaar also has several problems incurred during this metal to rubber bonding process. The cylindrical retainer portion seals of Levi require a continuous groove in the oven door front also significantly adding to the expense of manufacturing of the door.
The present invention overcomes the disadvantages of the prior art by providing an effective clipless, inexpensive integral oven door seal. The door seal of the present invention includes a sealing element and a retaining element. The sealing element includes an elastomeric seal body having a length substantially greater than its width and a pair of elongated resilient flanges depending from the seal body and running substantially the entire length of the elongated seal body. The retaining element generally includes a plurality of darts which are positioned between the flanges and depend from the seal body to secure the seal to a desired surface. Also a longitudinally extending support member may be positioned between the flanges to extend from dart to dart and aids in the sealing effect and stability of the oven door seal. The attachment surface, usually the oven door or front wall of an oven, has a plurality of apertures in which the darts are inserted to secure the oven seal onto the door surface.
By recognizing the spring-like qualities of rubber, the base of the seal was made concave so that the points of the darts can be allowed to pass easily beyond the inside of an aperture cut in the oven door or front wall of the oven. When beyond the metal, the dart points expand beyond the aperture width. When insertion pressure is stopped, the concave base that is flattened under insertion pressure resumes its concave shape and pulls the dart firmly against the wall around the aperture giving a firm attachment of the seal to the metal wall.
The concave section also serves a second purpose beyond the spring back. When cutting away the part of the dart not to be used in mounting the seal, in the customary flat bottom seal any extra rubber left on the bottom interferes with the sealing of the bottom against the metal. In production, it would be difficult to cut absolutely flush with the bottom leaving a bump on the bottom. With the spring back concave bottom on the seal, the two feet of the seal flanges can be folded back to cut the dart where it is not needed and form a support member. The support member does not need to be flush to be safely out of the position where it would interfere with the seating of the seal against the metal wall.
Any number of rubber darts can be used without increasing the cost (other than the original tooling cost on the oven front or door for the apertures). The seal can have its darts at the selected regular intervals which would provide the best grip, but in any event allowing the gasket or rubber strip to be cut continuously.
The feet on the bottom of the seal flanges also provide a low pressure deflection point where the pressure of the rubber darts (at the darts) or the pressure of the mating surface (away from the darts) will keep the feet in intimate contact with the metal wall effecting the best seal possible.
By cutting the rubber darts on centers slightly shorter than the aperture centers, two things are accomplished. When inserting the darts into the apertures, some elongation takes place in the rubber and the shorter centers will compensate for the stretch. After installation, the rubber returns to its original length giving a slight lateral stretch to the seal to keep its bend around the corners smooth and tight. It also would allow enough tension to absorb any thermal expansion that may occur during operation of the oven.
The cross sectional dimensions of the dart can be varied to permit ease of installation and the firmness of the grip to be regulated and maintained. The length of the rubber dart can also be varied, which makes it conceivable to shorten it to a length suitable to mount into a hole. Initially, the aperture will give more support and directional stability to the seal.
The all silicone rubber gasket or seal could be easily replaced if it became damaged. It is a true one piece gasket and if made from a good quality material can be removed and reused if necessary.
Other objects and advantages of the present invention will be apparent in the following specification, claims, and drawings.